Indentation of sandwiches using a plate model with variable kinematics and fixed degrees of freedom

• An analytical model with fixed d.o.f. is applied to study indentation of sandwiches.
• The crushing behaviour of soft cores is evaluated via 3D finite element analysis.
• The variable elastic moduli of the core are determined apart once at a time.
• The onset of damage is predicted using stress-based criteria.
• The damage growth is described employing mesoscale damage model.

A recent 3-D, 5 degrees of freedom, variable kinematics zig-zag homogenised model is used for studying sandwich indentation. This model cannot describe in a point-wise sense cells collapse, buckling, debonding failure, plastic yielding, or brittle fracture. Therefore, the progressive folding followed by densification of the core is described through mechanical properties variable with loading, which are computed apart once at a time through a 3D FEA discretisation of the core structure. Onset of damage is determined using stress-based criteria; degraded properties of failed regions are obtained from a mesoscale damage model. The results show efficiency and accuracy of this approach.